(Spring, 2002, pp. 5-7); copyright 2002 by The Nature Institute
Seeing the Rainforest
The following are some notes drawn from the rainforest sections of Andreas Suchantke's book, Eco-Geography: What We See When We Look at Landscapes (Great Barrington MA: Lindisfarne, 2001).
When Andreas Suchantke walks through the Amazonian or African rainforest, he senses an entire lifeworld straining upward, seeking the lightalmost, you might say, excarnating. The ecosystem has substantially detached itself from the earth, so that the walker finds himself traversing the forest's root zone. Giant, buttressing roots splay out from high up on tree trunks; the trees "seem to be standing on the earth rather than rooted in it. And, indeed, underground the roots hug the surface so closely that here and there they reemerge, coiling over the surface like great snakes" (p. 39). Everything you see immediately around you is root-like: "the hanging ropes of the lianas are scarcely distinguishable from the ubiquitous strangler fig and epiphyte tendrils, which are actually roots" (p. 40). (Epiphytes are plants growing non-parasitically upon other plants.)
Remove the thin layer of leaf debris on the forest floor, and you find an equally thin layer of rhizome-rich humus, which, if scratched away, reveals the sterile red soil immediately beneath. In the rainforest, Suchantke points out, the region of germination occurs less in the mineral-poor soil than upon it. The cycling of all important minerals occurs largely above ground. "Leaf litter and deadwood immediately fall prey to fungi, which live in such close symbiotic association with the shallow root systems of the trees that they prevent the nutrient cycles from dipping any lower and feed all decomposition products straight back into the upward nutrient stream of their host plants" (p. 112). Whatever does get into the ground is washed away by the heavy rains. "This explains why a tree can sprout only if the seed lands in the rotting remains of a fallen one" (p. 42).
Because of the continual loss of nutrients from the soil through leaching, the Amazonian rainforest would eventually face extinction if it were not for an unexpected nourishment borne on tradewinds from the northeast: mineral dust from the great sand storms of the Sahara desert.
Accordingly, the trees on Brazil's east coast (nearest to the Sahara) are the most heavily laden with epiphytesespecially bromeliads, which lack roots and are therefore wholly dependent upon wind-borne minerals.
The curious "detachment" of the rainforest's root zone from the soil has implications for modern practice. When a tropical rainforest is cleared by burning, the mineral ash provides an immediate shot of fertility for the new crops, but the benefit is short-lived. The sun quickly burns up any remaining organic matter and the soluble minerals are leached out of the soil, leaving only insoluble iron and aluminum compounds that sometimes harden into a rock-like crust. The land is ruined. Unlike in a temperate forest, "to destroy the world above ground is to destroy everything" (p. 43).
A Separate World in the Sun. If the root layer of the rainforest is displaced upward, so, too, is the herbaceous layer. In a temperate forest the green herbs and flowers lie immediately above ground. But to see these in the rainforest you have to look upward to the "hanging gardens" in the forest canopy. There you will find all manner of epiphytes accumulating on branches, "together with a full complement of mites, springtails, and even earthworms" (see illustration on previous page). Speaking of the African forest, Suchantke writes,
There is abundant bird life, too, high in the canopy. And "the birds share the scene with many species of frogs, which breed their tadpoles in the miniature ponds that form in the rosettes of bromeliads" (p. 110). In sum: whereas in temperate forests the layer richest in life processes and diversity of species is in or just above the ground, the tropical rainforests produce a corresponding layer in the canopy, high above ground level.
An Intense Monotony of Green. There is in all this, Suchantke notes, a remarkable paradox: "The earth's most luxuriant vegetation grows on the most infertile of soils" (p. 111). Just how luxuriant is brought home when you realize that, while rainforests account for only 3 percent of the earth's land surface, they contain almost one-third (29 percent) of terrestrial plant biomass. This mass includes a tremendous quantity of carbon (now being released into the atmosphere with the destruction of the forests) and also acts as a "gigantic saturated sponge" for water. The root systems catch much of the daily rainfall, and absorb the snow melt coming out of the mountains. The Amazon catchment area alone contains nearly one-fifth (18 percent) of all the fresh water flowing into the earth's oceans. The enormous quantity of water held by the biomass and released steadily into the atmosphere through transpiration has the same moderating effect as a large body of water, damping temperature extremes and keeping the air moist (pp. 96-97).
The vegetative lushness of the rainforest can present itself to the traveler as depressingly one-dimensional. The green leaf prevailsso much so that one can walk for hours without any change of scenery. "Finding a blossom provides very welcome relief for senses saturated by the endless monochrome of the lush foliage" (p. 100). Most blossoms, however, occur in the epiphytic layer overhead, close to the light. And even here, careful inspection reveals that the brightly colored parts are often sepals or bracts, while the blossoms themselves remain small and inconspicuous:
Some visitors find this unquenchable vegetative force oppressive. "Even scientists who have come to do research on the rainforest have been known to develop such a phobia against it that no power on earth would induce them to visit it a second time. They have the feeling of being trapped, smothered by its rampant vitality" (p. 108).
Suchantke relates the vegetative intensity of the rainforest to the relative scarcity of higher animal forms in the understory of the forest. In higher animals there begins to form an interior "reflective" space that is opposite to the vegetative polea space where growth forces are stopped and turned inward, toward sentience and consciousness. And, in any case, the protein-poor forests could not support an extensive, high-level food chain. It required the light-filled savannas to make possible the great herds of mammals evident on the African plains.
Clearing the Forest. European culture, Suchantke writes, would have been unthinkable without the clearing of the forests and the beginnings of agriculture.
But the healthy impulse in all this gave way (in Europe as elsewhere) to ecological devastation, and Suchantke now worries that the biosphere itself may not be able to survive the current wholesale destruction of the world's forests. His own aim is to understand the forests as a necessary preliminary for a wiser human engagement with theman engagement that would bring out their ancient virtues and help them to evolve in directions consistent with their own "striving."
With this in view, he points to a few promising ventures in rainforest-human partnership. And he speaks of much more in this book as well, including savannas and deserts, the Great Rift Valleys of Africa and elsewhere, the ecology of New Zealand, and the role of "juvenilization" in evolution. The book is a stimulating addition to the growing literature of a new, qualitative science. SLT
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